The present invention relates to an apparatus and a device, and a method for milking animals. The invention will now be described in conjunction with an apparatus and a method for milking cows. It is pointed out though that the present invention may likewise be employed for milking apparatuses and milking methods for milking sheep, goats, buffaloes, camels, dromedaries, llamas, donkeys, yaks, elks, horses, and other lactating animals.
The invention may be employed in conventional milking, machine milking, and in semi-automatic milking. Application is also conceivable in systems where cleaning of the teats and/or placing the teat cups to the animal teats occurs semi-automatically, fully automatically, robot-assisted and/or computer-controlled. It is also possible to provide semi- or fully automatic pre- or post-treatment of the teats e.g. by means of a dipping agent. Milking may be performed by quarter or a milk collection piece may be provided to receive milk hoses leading off the teat cups.
For machine-milking the prior art provides the so-called two-chamber teat cup principle. According to this principle, a liner is inserted in a teat cup sleeve so as to form two separate chambers namely, for one a teat cup internal chamber in which the teat is located, and for another a teat cup gap between the liner and the outer sleeve of the teat cup. The teat cup gap is typically referred to as the pulsation chamber and the teat cup internal chamber, as the teat chamber.
As the teat cup is placed on a teat in milking, a controlled negative pressure is applied to the teat cup internal chamber. In this way adherence of the teat cup is ensured. Furthermore, by way of the pressure difference generated between the teat cup internal chamber and the teat cistern, milk is drawn out of the teat and discharged.
By way of a continually applied permanent vacuum, however, liquids might accumulate in the teat tissue and specifically in the region of the teat tip. Thus, the closing mechanism for the teat provided in this region should not be kept open over time, i.e. continually. For this reason the prior art employs a pulsator intended to periodically apply different pressures to the gap between the teat cup sleeve and the liner, e.g. a vacuum alternating with atmospheric pressure.
The existing pressure differences cause the liner in the internal chamber of the teat cup sleeve to collapse as the teat cup gap is ventilated such that the liner bears snug against the teat where it remains during the rest phase. During the subsequent evacuation the liner is lifted off the teat, releasing the milk flow path that had been substantially closed during the rest phase. For the entire duration of milking the liner will periodically open and close with the milk flowing out of the teat while the liner is open. By way of the liner contacting the teat the teat tip will be massaged and the tissue relieved. The tissue fluid stemmed in the teat can be guided back to upper regions and thus back to blood circulation.
For effective milking it is useful or necessary to first stimulate the teats. Typically, the pulsator is operated at a noticeably higher frequency in the initial milking phase for stimulating the teat, e.g. approximately 300 cycles per minute for cows, while for the main milking phase a frequency of e.g. approximately 60 cycles per minute is set. In some cases the pulsator settings are made highly different, varying the time settings for each pulsation phase.
Other embodiments provide for positive pressure to be employed for the pressure difference in the so-called rest phase to be still higher with the liner closed.
Another approach to stimulating the teats attempts to positively influence teat massage by means of a different design of the liner. As a rule the prior art employs rotationally symmetric liners. Also, liners are known which are not round in cross-section in the region surrounding the teat but comprise oval or polygon areas.
A teat cup is known from EP 1 239 725 B1. Said teat cup comprises a liner connected with the teat cup sleeve through various radial walls. In this way the pulsation chamber comprises multiple finger-like chamber portions all of which are connected with one another and overall form one large vacuum chamber.
In the embodiments known from the prior art of the two-chamber teat cup principle described above the collapsing direction of the liner is basically always the same. This means that with the same teat cups consistently placed on the same teats of the animals to be milked, the teats will always be submitted to pressure loads in the same spots. This holds in particular in automatic milking systems where teat cup placement occurs robot-assisted. In these systems, automatic teat cup placement with the relatively consistent grasping and placing technique may result in that the teat cups will always be positioned the same relative to each teat. It has been observed in automatic milking systems that the teats flatten in the direction of the pressure loads. Recent studies have shown that the teats which otherwise respond highly sensitive will not be responsive to any kind of stimulation after two thirds of the milking operation.